1. Field of the Invention
The present invention relates to a measurement method for a granular compaction pile using a crosshole seismic test. More particularly, the present invention relates to a measurement method for a granular compaction pile using a crosshole seismic test, capable of measuring a diameter of the granular compaction pile, which is constructed in a soft ground as a foundation, according to the construction depth thereof through an S-wave measurement.
2. Description of the Prior Art
In a soft clay layer, a stone column serves as a base foundation to support an underground and to prevent the circular sliding failure and lateral guidance of an abutment for the purpose of accelerating consolidation of the foundation ground and the ground improvement.
In Korea, a sand compaction pile (SCP) method employing sand as compaction material has been extensively used in the past. However, due to the lack of sand and the price advance of the sand, a granular compaction pile (GCP) method, which employs a low-price aggregate, has been increasingly used in the construction to improve the ground.
In general, according to the construction using the GCP method, a casing having an inner diameter of 400 mm and equipped with a conic shoe is inserted into the ground by a desired depth and a dose of crushed stone (diameter 400 mm and height 3 m) is input into the casing. In this state, the casing is drawn by 3 m and then the casing is reinserted into the ground by 2 m to perform compaction work. This compaction work is carried out until the crushed stone having the diameter of 400 mm have the desired diameter of 700 mm. This compaction work repeats in the unit of 1 mm until the granular compaction pile work can be completed up to the ground surface.
The integrity evaluation of the granular pile is assumed based on the dose of the crushed stone input into the casing and the insertion depth of the casing. However, this type of integrity evaluation may not ensure the continuous structure having the constant diameter and difficulty remains in finding defects in the pile.
In addition, the ground around the granular pile is excavated to check the granular pile with the naked eyes, or a core is sampled from the granular pile by boring the granular pile to check the desired diameter of the granular pile.
However, the above methods may not find diameter variation of the granular pile in detail and may cause damage to the granular pile.